1. Field of the Invention
The present invention relates, in general, to ventilated shoes and, more particularly, to a structural improvement in such shoes for more effectively ventilating the interior of the shoes by interposing a midsole, made of a foam resin and provided with a ventilation means, between the inner and outer soles of a shoe. The invention also relates to a device and process for producing such ventilated shoes.
2. Description of the Prior Art
As well known to those skilled in the art, the feet of most people wearing shoes are wet with perspiration and dissipate heat, so that the air inside the shoes dampens and thereby causes propagation of harmful germs on the feet and gives out a bad smell. The above problems caused by the perspiration and heat inside the shoes may be overcome by ventilating the interior of the shoes. In an effort to achieve the above object, shoes provided with ventilation means are proposed and commercialized. Known ventilation means for shoes is composed of a ventilation port, which is provided on the inside wall of the shoe body for causing the interior of the shoe to communicate with the atmosphere. The above ventilation means also has an air cap, which is installed on the outside wall of the shoe body.
The shoes with the above ventilation means may be produced by a cementing process or an injection molding process. In the cementing process, the body and outer sole of a shoe are separately produced prior to tightly bonding the outer sole to the bottom (inner sole) of the shoe body. In order to bond the outer sole to the inner sole during the above cementing process, an adhesive sealer is applied to both the lower surface of the inner sole and the top surface of the outer sole. Meanwhile, in the injection molding process, a midsole, which is made of a foam resin, is interposed between the inner and outer soles prior to integrating the inner, mid and outer soles into a single structure by compressing them.
The injection molding process, which is connected with this invention, may produce various types of shoes with the various uses and configurations. For ease of description, a safety shoe, which is used for protecting a foot from injury in various industrial fields, is an example of the shoes produced by the injection molding process connected with this invention. However, it should be understood that the injection molding process may produce other types of shoes, such as sports shoes and climbing shoes.
FIG. 1 shows the sole-structure of a typical safety shoe with a shock absorbing and reinforcing means. As shown in FIG. 1, the typical safety shoe has a cushion midsole 4, which is interposed between the bottom (inner sole) 3 of a shoe body 1 and an outer sole 2 prior to integrating the inner, mid and outer soles into a single structure by compressing them. In addition, it is preferable to interpose a metal reinforcing plate 5 between the midsole 4 and the outer sole 2.
The above midsole 4, which is made of a cushion material and is interposed between the inner and outer soles 3 and 2 of the shoe, has the same configuration as the inner and outer soles. The cushion midsole 4 absorbs and intercepts the shock applied to a foot while stepping, thus protecting the foot from the shock.
The above safety shoes with the shock absorbing means effectively protect the feet of workers from dangerous objects by the metal reinforcing plate 5 and effectively absorbs shock, which is applied to the feet and knees of the workers, by the cushion midsole 4.
FIG. 2 shows the construction of a typical rotary press injection molding machine 10, which is used for producing the above safety shoes. The injection molding machine 10 includes a plurality of plastic injection molding units 14, which are regularly arranged in a circle on a rotary disc 12. The above rotary disc 12 is held on a circular die 16. Two solution feeders 18 and 20 are installed on the edge of the die 16 at diametrically-opposite positions.
The construction of the top mold section of each injection molding unit 14 is shown in FIG. 3. As shown in FIG. 3, the top mold section of each injection molding unit 14 includes a shoe holder 24 and a top mold 26. The above holder 24 and top mold 26 are held on the diametrically-opposite positions of a turret 22, so that the holder 24 and top mold 26 are rotated along with the turret 22. The unit 24 also includes a bottom mold 28. The above top mold section, including the turret 22, holder 24 and top mold 26, is movably held by a guide column, so that the top mold section vertically moves up and down relative to the bottom mold 28 under the guide of the guide column.
In an injection molding process for producing the safety shoes using the above injection molding machine 10, one injection molding unit 14 is positioned on the same line as the first solution feeder 18 as a result of the rotating motion of the rotary disc 12. In the above state, a foamless first solution 30 is injected from the head 36 of the first solution feeder 18 into the bottom mold 28 of the unit 14 as shown in FIG. 4. Due to the rotating motion of the rotary disc 12, the unit 14 with the first solution 30 moves to the diametrically-opposite position, thus being positioned on the same line as the second solution feeder 20. While the unit 14 moves from the first feeder 18 to the second feeder 20, the top mold section vertically moves down onto the bottom mold 28, so that the top mold 26 compresses the first solution 30 inside the bottom mold 28 as shown in FIG. 5. The first solution 30 inside the bottom mold 28 is thus formed into the outer sole 2. When the unit 14 with the formed outer sole 2 is positioned on the same line as the second solution feeder 20, a foam second solution 32 is injected from the second feeder 20 onto the molded outer sole 2 inside the bottom mold 28. The above second solution 32 is formed into the midsole 4 of the shoe.
As shown in FIGS. 6 to 9, while the injection molding unit 14 with the second solution 32 in its bottom mold 28 moves from the second feeder 20 by the rotating motion of the rotary disc 12, the separately-produced shoe body 1 is seated on the shoe holder 24. After seating the shoe body 1 onto the holder 24, the turret 22 of the top mold section is rotated at an angle of 180.degree. C., so that the shoe holder 24 with the shoe body 1 is directed downward onto the bottom mold 28. The top mold 26 in the above state is directed upward.
The shoe body 1 held on the shoe holder 24 vertically comes down onto the bottom mold 28 thereby being brought into contact with the second solution 32 inside the bottom mold 28. In the above state, the second solution 32 inside the bottom mold 28 has not been completely hardened into the midsole 4, so that the bottom (inner sole) 3 of the shoe body 1 is bonded to the midsole 4 into a single structure. Of course, the midsole 4 in the above state is also bonded to the outer sole 2 into a single structure, so that the inner sole 3, mid sole 4 and outer sole 2 of the safety shoe are tightly bonded together into a single structure.
In the typical safety shoe produced by the above injection molding process, both the cushion midsole 4 and the metal reinforcing plate 5 are interposed between the inner and outer soles 3 and 2 and are integrated with the soles 3 and 2 into a single structure. The above safety shoe thus has a cushion sole structure due to the midsole 4, and a reinforced sole structure due to the metal plate 5. The above cushion sole structure of the safety shoe somewhat effectively absorbs and intercepts the shock, which is applied to the foot of a wearer from the ground while stepping. Meanwhile, the above reinforced sole structure protects the foot of the wearer from a sharpened material on the ground.
However, the above safety shoe, which exclusively has the cushion and reinforcing means for absorbing shock and protecting the wearer's foot from a sharpened material, has the following problems. That is, the above safety shoe is not provided with a means for ventilating the interior of the shoe. Therefore, the foot in the above shoe is wet with perspiration and dissipate heat, so that the air inside the safety shoe dampens and thereby causes propagation of harmful germs on the foot and gives out a bad smell.